Atrial fibrillation in mitral stenosis: histologic, hemodynamic and metabolic factors.

We examined the histologic, hemodynamic and metabolic factors associated with rheumatic mitral stenosis. Eighteen patients comprised three groups: Group I - 7 patients in sinus rhythm; Group II - 5 patients in intermittent atrial fibrillation; Group III - 6 patients in chronic atrial fibrillation. The left atrial dimension was determined by echocardiography. Left atrial pressure, mitral valve gradient, mitral valve area and the presence or absence of calcium in the mitral valve were determined at catheterization. The left atrial appendage was removed during open heart surgery and the tissue was analyzed for cell size, percent fibrosis and content of cyclic AMP and GMP. There was no difference between the groups in pulmonary capillary wedge pressure, mitral valve gradient, mitral valve area or the presence of calcium. The Group I left atrial dimension (51 +/- 2 mm, means +/- SE) was significantly smaller than that of Group III (56 +/- 2 mm, P less than 0.05). Group II was not different from Groups I or III. Although the concentration of cyclic AMP did not differ among the groups, the cyclic GMP was significantly depressed in Group III (0.15 +/- 0.02 fmol/microgram protein) when compared to Group I (0.24 +/- 0.05 fmol/microgram protein, P less than 0.01). Group II had intermediate values which did not differ from Groups I or III. The percent fibrosis was greatest in Group III (34.8 +/- 1.8%) and least in Group I (27.2 +/- 2.8%, P less than 0.05). There was no difference in cell size among the groups. Although atrial fibrillation may lead to some of these irregularities, a depressed cyclic GMP, increased fibrosis and increased left atrial dimension may play a role in the pathogenesis of irreversible atrial fibrillation.

Human myocardial histologic characteristics in congestive heart failure.

The purpose of this study was to identify the histologic characteristics of human myocardium in congestive heart failure (CHF) by cellular hypertrophy, nuclear area, endocardial thickness, and percentage of fibrosis and to correlate histologic findings to cause, severity, and duration of disease. Right ventricular endomyocardial biopsies from 109 patients were quantitatively analyzed. Ten patients with normal cardiac history, physical examination results, and cardiac function served as the control group. The remaining patients were divided into the following groups: those treated with doxorubicin (n = 18), and those with chest pain with normal coronary arteries (n = 8), familial CHF (n = 3), CHF associated with myotonic dystrophy (n = 3), peripartal CHF (n = 2), valvular CHF (n = 9), alcohol-induced CHF (n = 13), postviral CHF (n = 6), or idiopathic CHF (n = 36). Linear regression analyses showed a strong correlation between cell diameter and nuclear area (r = .70, p less than .001) and weaker correlations between amount of fibrosis and cell diameter (r = .30, p less than .005) and fibrosis and nuclear area (r = .29, p less than .005). Results of function studies and histologic measurements (e.g., echocardiographically measured change in the minor-axis dimension of the left ventricle with systole and cell diameter) correlated poorly (r = -.33, p less than .005). Duration of dyspnea did not correlate with any histologic factor. Within the normal group there was a direct correlation of cell diameter with age (r = .67, p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Attempt to prevent doxorubicin-induced acute human myocardial morphologic damage with acetylcysteine.

Doxorubicin induced acute as well as chronic myocardial morphologic alterations. Twenty patients with normal cardiovascular function were randomized to 2 groups based on age and dose of doxorubicin. Group I received placebo 1 hour before doxorubicin administration; group II received acetylcysteine (N-acetyl-L-cysteine) (Nac) 1 hour before doxorubicin. Endomyocardial biopsies were performed at base line at 4 and 24 hours after doxorubicin administration. Biopsy tissue was viewed by electron microscopy, and stereoscopic techniques were used to determine tubular and mitochondrial area. The change of the tubular area was similar in the 2 groups, was maximum at 4 hours, and was proportionately spread throughout the cell. The mitochondrial swelling was also similar in the 2 groups and proportionate throughout the cell but was maximum at 24 hours. This study demonstrated that the acute doxorubicin-induced damage was diffuse and not prevented by Nac.

Differentiating characteristics of myocardial nuclei in cardiomyopathy.

Myocardial tissue obtained by endomyocardial biopsy was semiquantitatively evaluated for nuclear and nucleolar characteristics in six groups of patients: patients with normal cardiac function (group 1), doxorubicin-induced cardiomyopathy (group 2), idiopathic cardiomyopathy (group 3), alcoholic cardiomyopathy (group 4), post-viral cardiomyopathy (group 5), and chronic valvular heart disease (group 6). From each patient, ten nuclei containing nucleoli were examined and rated on the basis of the following characteristics: chromatin clumping, number of fibrillar centers per nucleolus, nucleolonemal structure, size of nucleolus, number of nucleoli per nucleus, and stage of nucleolar change. Mean values for the nuclear characteristics in each group were compared with normal values using the unpaired t test. In the doxorubicin treated group there were significantly increased chromatin clumping, decreased fibrillar centers, decreased nucleolonemal structure, and increased numbers of contracted nucleoli (indicating later stage). These changes may be linked to lowered nuclear and nucleolar activity. In the idiopathic and post-viral groups, characteristics were consistent with increased nuclear and nucleolar activity. There were no significant changes from normal in the nucleolar features of either the alcoholic or valvular groups. Further comparisons between groups using one-way analysis of variance and multivariate statistical analysis support the conclusion that there are significant differences in the nuclear and nucleolar characteristics of these groups.

Early changes in human myocardial nuclei after doxorubicin.

Ten nuclei from the endomyocardial biopsies for each of the following 32 patients were examined by electron microscopy: seven patients before and then four and 24 hours after treatment with first-dose doxorubicin; seven patients before and four and 24 hours after treatment with first-dose doxorubicin plus N-acetyl cysteine; nine patients with doxorubicin induced cardiomyopathy; and nine patients with idiopathic congestive cardiomyopathy. Five criteria were used to semiquantitatively compare nuclei and nucleoli from each group. The most dramatic changes in nuclear and nucleolar morphology were seen four hours after doxorubicin administration. Nucleoli were smaller, contracted or segregated and contained fewer fibrillar centers and a collapsed or fragmented nucleolonema. The addition of N-acetylcysteine to treatment did not alter these results. By 24 hours, nuclei had returned to the pre-treatment status. Long-term doxorubicin therapy produced increased chromatin clumping and slightly contracted nucleoli. The idiopathic congestive cardiomyopathic nuclei differed significantly from these doxorubicin cardiomyopathic nuclei in the decreased amount of chromatin clumping and the increase in fibrillar centers and nucleonema pattern. It is concluded from this study that: (1) doxorubicin markedly alters the morphology of the human myocardial nucleus and nucleolus four hours after treatment, but these changes diminish by 24 hours; (2) N-acetylcysteine treatment fails to prevent these changes; and (3) the nuclei and nucleoli of chronic doxorubicin-induced cardiomyopathy differ significantly from other congestive cardiomyopathies, but do resemble changes seen four hours after the first dose of doxorubicin.

Regression of myocardial cellular hypertrophy with vasodilator therapy in chronic congestive heart failure associated with idiopathic dilated cardiomyopathy.

Forty-nine patients with idiopathic dilated cardiomyopathy (IDC) were evaluated to determine the hemodynamic and morphologic effects of vasodilator therapy. Hydralazine (225 mg/day, H), isosorbide dinitrate (160 mg/day, I), and combination H + I therapy were compared with placebo (P) at baseline and after 3 months of continuous therapy. Thirty-three randomly assigned patients completed the study. Hemodynamic parameters included the echocardiographic percent change of left ventricular diameter (% delta D), the systolic time intervals ratio of preejection period to left ventricular ejection time (PEP/LVET), the pulmonary capillary wedge pressure, mean pulmonary artery pressure, cardiac index, systemic vascular resistance, and pulmonary vascular resistance. An endomyocardial biopsy was performed at baseline and after 3 months; the myocardial cell diameter of 50 cells per biopsy was measured. During the 3-month study 5 patients died; there was not a significant difference among the groups in the number of deaths. The % delta D and PEP/LVET did not change in the P or I groups but did improve significantly from baseline in the H and H + I groups. The pulmonary capillary wedge and mean pulmonary artery pressures and the pulmonary vascular resistance did not change in the P or H groups but did decrease significantly in the I and H + I groups. The P and I groups did not have improvement in systemic vascular resistance or cardiac index, whereas the H group had a decrease in systemic vascular resistance and an increase in cardiac index from 2.5 +/- 0.4 to 3.1 +/- 0.4 liters/min/m2 (p less than 0.05). The H + I group also had a decrease in systemic vascular resistance; the cardiac index increased from 2.3 +/- 0.4 to 3.1 +/- 0.4 liters/min/m2 (p less than 0.01). Myocardial cell diameter did not change in the P or I group. Cell diameter of the H group decreased from 25.4 +/- 3.1 microns at baseline to 23.1 +/- 3.8 microns (p less than 0.05) after 3 months of continuous therapy. The H + I group decreased its cell diameter from 23.9 +/- 3.7 to 22.2 +/- 2.2 microns (p less than 0.05). Compared with P and H, patients treated with I alone or H + I had a significant reduction of preload. In contrast to P and I, H alone and H + I elicited improvement in parameters of inotropy and afterload, and this improvement was accompanied by a reduction in cell diameter. Chronic therapy of heart failure with H and H + I effects a persistent augmentation of cardiac function and improvement of myocardial cellular morphology.

Cardiac evaluation of mitoxantrone.

Mitoxantrone is a synthetic anthraquinone that was developed through the doxorubicin analog program in hopes of retaining anticancer activity with less cardiotoxicity. This study evaluated 18 patients receiving mitoxantrone with serial noninvasive tests of left ventricular function and with endomyocardial biopsy. The echocardiograms and systolic time intervals demonstrated a trend to deterioration that did not achieve statistical significance. However, the nuclear angiographic ejection fraction significantly decreased from 61% +/- 6% (means +/- SD) at baseline to 58% +/- 5% (P less than 0.05) after 48 mg/m2 of mitoxantrone. The endomyocardial biopsies revealed tubular swelling, degeneration of mitochondria, minimal chromatin clumping, and myofibrillar lysis. This study has revealed mild but definite impairment of cardiac function and mild changes of myocardial morphology during mitoxantrone therapy. Although mitoxantrone is an effective chemotherapeutic agent, a direct comparison of mitoxantrone with doxorubicin is necessary to compare relative therapeutic to cardiotoxic ratios.